Increase logging in error case in valve.

Author: jcoleman

src/main/java/com/radiadesign/catalina/session/RedisSessionHandlerValve.java

@@ -48,7 +48,7 @@ private void storeOrRemoveSession(Session session) {
         }
       }
     } catch (Exception e) {
-      // Do nothing.
+      log.error("Error storing/removing session", e);
     }
   }
 }